Tanning medium.



ANDREW 'IURNBULL.

OF LIVERPOOL. AND THOMAS BURNELL GARMICHAEL, OF

WATERLOO, NEAR LIVERPOOL, ENGLAND; SAID CARMICHAEL ASSIGNOR T0 SAID TURNBULL.

TANNING MEDIUM.

No Drawing.

To all whom it may concern Be it known that We, ANDREW TURNBULL and THOMAS BURNELL CARMIQHAEL, subjects of the King of Great Britain, residing at Liverpool, and Waterloo, near Liverpool, respectively, both in the county of Lancaster and Kingdom of England, have invented certain new and useful Improvements in Tanning Mediums, of which the following is a specification.

In 'the process of converting hides and skins into leather, if the .solutions of the tanning agents employed at the commencement be too strong, the outside fibers quickly become tanned and more or less impervious to the penetration of the tanning agent, so that the inside fibers either remain untanned or become only lightly tanned. On the other hand, by the usual process beginning with very weak liquors and continuing with liquors of gradually increasing strengths, the time spent in the operation is very considerable and there is a great waste of material.

Now, our invention is designed to enable a comparatively strong solution or solutions of very varying strength, to be used and yet avoid these evils. At the same time the resultant leather is fuller and otherwise greatly improved from absorption of the special material used and the more thorough fixation of the tanning agent.

Our process consists in preparing and utilizing the jellies or colloidal liquors which are formed when starch granules are heated to a suitable temperature with aqueous solutions of vegetable, artificial or mineral tanning agents. For this 4 purpose we use starch, or natural products containing starch as their principal ingredient with a minimum of gluten, such as ordinary laundry starch, farina, flour from sago, arrowroot. tapioca, cassava, manioc, &c.

When starch is mixed with an aqueous liquid and the temperature raised to'180 F., the' starch granules, as is well known, swell and imbibe the liquid to form a jelly or colloidal liquor. If the aqueous liquid employed be an extract of vegetable tannins, these dissolve in the jelly and on cooling remain in a state of whole or partial solution. This colloidal condition of the tanning Specification of Letters Batent.

Patented Dec. 17, 1918.

Application filed July is. 1917. Serial No. 180.877.

power of quick and even penetration. Further, the addition of a suitable vegetable tanning material to the bluish green chrome jelly, causes the formation of a more'or less brown jelly which readily penetrates hide fiber yielding an excellent combination leather of chrome and vegetable tanning. The clear jelly formed by basic aluminium salts yields a very satisfactory full White leather, Which readily forms a good combination leather when suitably treated vwith vegetable tannins.

By treating properly prepared pelt, which is hide orskin freed from hair and rough flesh, by the preliminary processes in a tannery, with one or other of the above described jellies or colloidal liquors, in

layer (laid flat), or in suspension in pits or by drumming, the tanning agents in their colloidal condition with starch, quickly and evenly penetrate the pelt fibers, converting them into leather with specially desirable qualities of fullness, susbtance, firmness and weight.

The strengths of the tanning agents employed, and the proportion and quality of starch used in preparing the above described jellies or colloidal liquors, may be varied greatly, and the jellies or colloidal liquors may be utilized until nearly exhausted or they may be concentrated by evaporationor addition of more starch or tanning agent as desired. The colloidal starch helps to equalize the strength throughout the mass, and appears to form with the'tan'ning agent a true colloid. In this condition the tanning agent is presented to the fibers with the astringency sufficiently reduced to avoid what is technically known as case-hardening being just so that it is absorbed in regulated quantity by all the fibers even to the center of the thickest hide. In addition, when the resultant leather is dried, the

tanning materials are more thoroughly fixed or belting leather to get the requisite. tullagainst the solvent action of water than lh ness. 4 the case with ordinary leather.

I'll/(mic combimlfl'un hum/u c. In-order to more iully describe the nature of our invention, we append by way of illustration four cases of its practical application.

Vegetable mun-aye. V In a copper steam-jacketed pan, to

In the basic chrome liquor described above under Chrome tannage, before adding the starch dissolve 750 lbs. plantation gambler in the chrome liquor, then add the starch and proceed as before. lleavy butts require considerably longer in this chrome gallons old blended tan-liquor, such as 1 vegetable tannin combination jelly to color commonly used in a mixed sole. leather tanevenly th h, S h t, i il bi. nage, strengthened to 125 barkometer .wlt nation leather can be obtained by following a suitable tanning extract such as 11 ghtly blthe above described chrome tauuage with a sulfited quebracho, carefully stir n 250 lbs. starch gambicr taunage.

finely powdered starch, and with constantstirring quickly raise the temperature to 180 F. Keep at this temperature forhttecn minutes and cool. Thejelly is put into .1 lam runway c,

in a copper steam-jacket pan dissolve 9.50 lbs. aluminium sulfate in 350 gallons warm through the butts may be suspended in 150 an ordinary tan-pit and delimed sole leather water, and slowly add with constant stirbutt pelt is laid fiatgraiu down in it. using ring 30 lbs. soda ash dissolved in 2:) gallons wooden plunger-s to push the butts down and warm water. With the tei'nperature not having strings attached to two corners for convenience in removing. There is no need dered starch, and with ma-t, ti i for frequent handling to insure even color,- quickly raise the temperature to 180 F. but after two days it is advisable to utilize Keep at this temperature for fifteen minutes thepartly spent jelly for a fresh pack of and cool. This jelly is put into an ordinary butts, and to put the partly tanned butts fortan-pit and delimcd butt pelt of thick subward into a fresh jelly from which they need stance laid flat in it for two or more days not be moved for four days, the jelly from 'will be found evenly penetrated, a fuller which they are then taken being used for the leather being obtained by giving the longer pack of butts wvhich follows them. The time. This leather suitably treated with. butts are thusmoved forward until even the. starch gambier jelly or strong liquor of thickest parts on cutting show evenly olgambier gives an excellent alum vegetable ored through, which seldom requires more tannin combination leather.

than three weeks. Sulficient acetic or other In the appended claims the word starch suitable organic acid should be added to the will be employed as denoting ordinary tan-pits to insure reasonable plumpuess and starch or materials consisting mainly of.

above 100 '1 stir in ZaSOlbs. finely pow firmness according to the character of the starch in which the degree of hydrolysis is leather required. Vhen quite colored but low; When potato starch for instance,

is subjected to conditions leading to hydrolybarkometer warm chestnut-wood extract sis, the. first result will be the disruption of liquor to increase the solidity and weight, the starch cells; this may be effected by before finishing for, sole leather in the usual warming with .water to 180 F. The next way. Dressing leather would not require result will be the production of the so-called this final treatment.

lUhrome manage.

In a co per steam-jacketed pan dissolve soluble starch. So far each of these products, namely, gelatinized starch and soluble starch are still starch in the strict chemical sense of the word, and as the word is 500 lbs. 0 rome alumin 350 gallons warm l y d i th app nd d laims; each water, and slowly add Wlth constant stirring product gives the characteristic starch re- 6.) lbs. soda ash dissolved 1n 25 gallons warm action with iodin. 'It now the starch is furwater. lV th the temperature not above ther subjected to hydrolytic influences, the 100 F. stir n 250 lbs. finely powdered starch reaction will gradually decrease in starch and wlt-ll n nt lll g quickly intensity and't-he material will run through ra se the temperature to 180 F: Keep at .a whole gamut of degradational changes unthis temperature tor fifteen minutes and Vtil finally dextrin and dextrose are obtained. cool. Thls elly is put into an ordinary tan-" 'It.will be understood therefore that the word pit and del1med sol e leather butt pelt is laid starch is hereafter employed to denote flat gram down m it, using wooden plungers bodies in which such hydrolytic action is but to push the butts down and 'havmg strings slight, which bodies form jellies with the attached to two corners for convenience in tanning agent, as distinguished from the removing. Vlt-lllll two'days the butts will bodies such as dextrin and dextrose at the be found evenly chromed through, but it is other end of the above described gamut of advantageous to give about a .week for sole changes.

We declare that What we claim is 1. A. process of preparing a tanning medium which consists in combining a tanning agent with starch including the step of gelatinizing the starch by heating it to about 180 F. 1n presence of water.

2. An improved tanning medium consisting of .a tanning agent plus gelatinized starch.

3. An improved tanning medium consisting of a mineral tanning agent plus gelatinized starch.

4. An improved tanning medium consisting a chrome tanning agent plus gelatinized signed our names this 26th day of J line 1917, 20

in the presence of two subscribing witnesses.

I ANDREW TUBNBULL. i

THOMAS BURNELL GARMIGHAEL. Witnesses:

P. THOMPSON, CHAS. LESLIE. 

